A protester in Homs throws a tear gas canister back toward security forces. (Stringer/AFP/Getty Images)

Rebel and government forces in Syria began a four-day cease-fire on Friday to observe the holiday Eid al-Adha. But, according to a report from activists that the Associated Press says is "consistent with their reporting," the Syrian military only made it part way through two Day Two before violating the truce. 

Syrian warplanes allegedly bombed parts of the Damascus suburb Arbeen, according the report, which says that eight were killed and "many" wounded. If true, it's not a great sign for the remaining two and half days of the ceasefire. Beyond this weekend, it could even further damage the Syrian government's credibility in internal and international negotiations, making future deals more difficult.

The onus of observing the ceasefire would seem to rest disproportionately on the Syrian government, which still enjoys the overwhelming preponderance of military force. Still, it was not the first to use force following the beginning of the ceasefire. The Washington Post reported on Friday that one extremist rebel group had refused to observe it from the start:

The [Britain-based Syrian Observatory for Human Rights] also reported that fierce clashes had erupted between government forces and rebels east of the strategic town of Maarat Numan in northern Idlib. Fighters with the extremist Jabhat al-Nusra Front, which has vowed not to observe the truce, attacked a checkpoint, prompting the army to shell a nearby village, the Observatory said.

Armed conflict, it seems, has a momentum all its own.